Numerical Research On Back Silting In The Deep-water Navigation Channel On Muddy Coast

The sedimentation of the deep-water navigation channel on muddy coast hasbeen a prominent problem in the construction of port and channel, the surveyof back-siltation often is conditioned by many factors, is faced with many difficultiesand challenges, the numerical research on back silting in the deep-water navigationchannel on muddy coast not only can save a lot of cost, also can forecastthe siltation intensity of channel under extreme sea conditions, it is of greatimportance to the construction of port and channel on muddy coast. The research isbased on Jinghai bay area-a muddy compound bay. The mathematical models ofwave, tidal current and sediment are used to carry out the numerical simulationresearch from the following three aspects:First, MIKE21Spectral Wave module is used to build a wave mathematicalmodel of the yellow sea with wind field data of2004and2005, through comparingsimulated values and measured values shows that wave simulation result is good.Then, the MIKE21HD FM and MIKE21MT FM are used to simulate tidal current,sediment conditions of Jinghai bay area during the spring tide and neap tide.According to the date of measured position, tidal level, flow velocity, flow directionand suspended sediment concentration are compared with the observed value; thevalidation result is good in general.Secondly, under the action of the pure tide, the erosion and deposition of200,000DWT channel is simulated in each season; under the combined action of wind, waveand current, the erosion and deposition of100,000DWT channel and200,000DWT channel are simulated in each season, back silting of the transverse and verticalsection of channel have been compared and analyzed. The simulation results ofdifferent working conditions show that channel deposition thickness and siltationrange is increased with the increase of channel excavation depth; back siltingdecreases as the channel extends to the deep sea. After joining the influence of thewind and waves, the back silting of channel enhanced obviously, and this effect is more obvious in summer that wind and waves are strong.Finally, by reference to relevant hydrological norms and previous researchresults, twelve kinds of extreme sea condition are designed, the suspended sedimentdistribution, bed thickness change and back silting of channel are forecast andanalyzed after the influence of extreme sea condition lasts24hours. The results showthat extreme sea condition aggravates the back silting of the channel in a short periodof time, its sediment deposition of a day is equivalent to several times or even adozen times at ordinary times, it should be taken seriously in the engineeringconstruction.